code: def _WeightedCrossEntropy(self, logits, targets, pos_coeff):
      assert len(logits) == len(targets)
      pred = [1 / (1 + exp(-x)) for x in logits]
      eps = 0.0001
      pred = [min(max(p, eps), 1 - eps) for p in pred]
      return [
          -z * pos_coeff * log(y) - (1 - z) * log(1 - y)
          for y, z in zip(pred, targets)
      ]
  
imports: import math
  import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import gradient_checker
  from tensorflow.python.ops import gradients_impl
  from tensorflow.python.ops import nn_impl
  import tensorflow.python.ops.nn_grad
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the WeightedCrossEntropyTest obj's underlying member method code with example usage: obj._WeightedCrossEntropy(logits, targets, pos_coeff) and returns: unknown